<!DOCTYPE HTML>
<style>
body { width: 450px }
body, select { font-size: 34px }
</style>
<!--
In a 450px container, the minimum font size at 15em per line is 30px.
This means we map 0px-45px into 30px-45px, so 12px gets mapped to 34px.
-->
<select size="3">
  <optgroup label="Counties">
    <option>Arlington
    <option>Fairfax
    <option>Loudon
    <option>Prince William
  <optgroup label="Cities">
    <option>Alexandria
    <option>Falls Church
    <option>Manassas
    <option>Manassas Park
</select>
